NGC 6633 is a solar metallicity, young open cluster. In addition to providing useful information from an asteroseismic point of view, it has the additional attractiveness of being located in the potential field of view of the COROT space mission (indeed, it is currently included in the primary target selection list). We report on some preliminary

In this contribution, we study the different stellar configurations that can produce signals resembling those produced by a transiting planet. We list several strategies to recognize these false alarms. For the most common configurations, we delineate which of these strategies are able to detect them. The case of an eclipsing binary of similar

In the light of several recent developments we revisit the phenomenon of galactic stellar disk truncations. Even 25 years since the first paper on outer breaks in the radial light profiles of spiral galaxies, their origin is still unclear. The two most promising explanations are that these 'outer edges' either trace the maximum angular momentum

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We present low-resolution (R=900) optical (576.1-1051.1 nm) spectroscopic observations of 40 candidate very low mass members in the Upper Scorpius OB association. These objects were selected using the I, J, and K photometry available in the Deep Near-Infrared Survey (DENIS) database. We have derived spectral types, and we have measured Hα and Na I

In a recent preprint, Pepper et al. (2002) evaluate the sensitivity of photon-noise limited transit searches for habitable planets. They conclude that these searches have the largest chance of success if they are optimized toward the surveying of M stars. Such an optimisation implies several constraints and trade-offs. The principal one is that M